Getting Started with Hackster EEDU Kits & Arduino IoT Cloud

Introduction

This tutorial is designed to be a quick guide to help users build innovative projects using DFRobot & Hackster EEDU kits with the Arduino IoT cloud. The EEDU kits are all built around an Arduino-compatible, ESP32-based FireBeetle 2 Board and include rich application-specific peripherals such as AI camera HuskyLens, multifunctional Environmental Sensor, URM37 ultrasonic sensor, DFPlayer module, and so on. In this tutorial, we demonstrate three cases involving AI, IoT, and environmental sensing respectively, and also offer some guidelines for getting started with Arduino IoT cloud.

How to Get Documents Resources

1. Click to open the EEDU Kit wiki page, then you will find all the product information here. Each product's wiki is linked to the table at the position marked in orange below.

2. On the wiki page, you can find the related library, connection diagram, sample codes, and so on.

Application Cases

Please follow the steps above to get details about using each hardware unit. Here we only provide you with some basics in four demos: a face recognition switch, an anti-theft alarm device, environmental data monitoring, and VOC index monitoring.

1. Face Recognition Switch

Description

Use the DFRobot HuskyLens camera to recognize the human face. If a learned face is recognized, the relay turns on. If the face is unlearned, it stays off.

Hardware List

1. HuskyLens AI Vision Sensor ×1

2. FireBeetle 2 ESP32-E IoT Microcontroller ×1

3. Digital Relay Module ×1

Connection

Connect the hardware using the DuPont wires that come with the kit.

Upload Codes to Arduino Cloud Editor

1. Sign up and log in to www.arduino.cc.

2. Open the Arduino cloud editor.

3. Follow the prompts to install and run the Arduino Create Agent, which will provide the following functions:

• Identify the Arduino board and other supported devices connected to the computer via USB
• Upload the sketch from the Web browser to the board via USB or the network
• Read data from the serial monitor, and write data

When completing the steps above, you will see the agent icon in the system tray. Make sure it is black/green. If it's grey, click it and select "Resume Agent".

4. Create a new sketch. Copy and paste the sample codes into the program editing area.

#include "HUSKYLENS.h"
HUSKYLENS huskylens;
//HUSKYLENS green line >> SDA; blue line >> SCL
void printResult(HUSKYLENSResult result);

void setup() {
    Serial.begin(115200);
    Wire.begin();
    while (!huskylens.begin(Wire))
    {
        Serial.println(F("Begin failed!"));
        Serial.println(F("1.Please recheck the \"Protocol Type\" in HUSKYLENS (General Settings>>Protocol Type>>I2C)"));
        Serial.println(F("2.Please recheck the connection."));
        delay(100);
    }
    pinMode(D6, OUTPUT);
}

void loop() {
    if (!huskylens.request()) Serial.println(F("Fail to request data from HUSKYLENS, recheck the connection!"));
    else if(!huskylens.isLearned()) Serial.println(F("Nothing learned, press learn button on HUSKYLENS to learn one!"));
    else if(!huskylens.available()) Serial.println(F("No block or arrow appears on the screen!"));
    else
    {
        Serial.println(F("###########"));
        while (huskylens.available())
        {
            HUSKYLENSResult result = huskylens.read();
            printResult(result);
        }    
    }
}

void printResult(HUSKYLENSResult result){
    if (result.command == COMMAND_RETURN_BLOCK){
        Serial.println(String()+F("Block:xCenter=")+result.xCenter+F(",yCenter=")+result.yCenter+F(",width=")+result.width+F(",height=")+result.height+F(",ID=")+result.ID);
       if(result.ID==1){
         digitalWrite(D6, HIGH);
         delay(2000);
         digitalWrite(D6, LOW);
        }
    }
}
#include "HUSKYLENS.h"
HUSKYLENS huskylens;
//HUSKYLENS green line >> SDA; blue line >> SCL
void printResult(HUSKYLENSResult result);

void setup() {
    Serial.begin(115200);
    Wire.begin();
    while (!huskylens.begin(Wire))
    {
        Serial.println(F("Begin failed!"));
        Serial.println(F("1.Please recheck the \"Protocol Type\" in HUSKYLENS (General Settings>>Protocol Type>>I2C)"));
        Serial.println(F("2.Please recheck the connection."));
        delay(100);
    }
    pinMode(D6, OUTPUT);
}

void loop() {
    if (!huskylens.request()) Serial.println(F("Fail to request data from HUSKYLENS, recheck the connection!"));
    else if(!huskylens.isLearned()) Serial.println(F("Nothing learned, press learn button on HUSKYLENS to learn one!"));
    else if(!huskylens.available()) Serial.println(F("No block or arrow appears on the screen!"));
    else
    {
        Serial.println(F("###########"));
        while (huskylens.available())
        {
            HUSKYLENSResult result = huskylens.read();
            printResult(result);
        }    
    }
}

void printResult(HUSKYLENSResult result){
    if (result.command == COMMAND_RETURN_BLOCK){
        Serial.println(String()+F("Block:xCenter=")+result.xCenter+F(",yCenter=")+result.yCenter+F(",width=")+result.width+F(",height=")+result.height+F(",ID=")+result.ID);
       if(result.ID==1){
         digitalWrite(D6, HIGH);
         delay(2000);
         digitalWrite(D6, LOW);
        }
    }
}

5. Import the library. Download the HuskyLens Arduino library zip first, and then import it to the Arduino Cloud. (Skip it if you don't need to use a library)

The Arduino library provides additional functions

• It mainly contains some driver files for sensors or actuators and some common functions
• For beginners, you only need to know how to use the functions provided in the library without getting deeply into how these functions or drivers are implemented, which greatly reduces development difficulty

6. Connect ESP32 to the computer via a Type-C cable and upload the program to the board.

7. Select the corresponding board & port, click to upload program, and wait for the uploading success.

Result

When a learned face is recognized by HuskyLens, the relay turns on; when an unlearned face is recognized, it stays off.

2. Anti-theft Alarm Device

Description

The PIR sensor detects the presence of human beings (detected: 1; not detected: 0). If the controller receives signals from the sensor and human presence is determined, report the message "intrusion alarm" to Blynk.

Hardware List

1. FireBeetle 2 ESP32-E IoT Microcontroller ×1

2. Gravity: Digital PIR (Motion) Sensor for Arduino ×1

Connection

Upload Codes to Arduino Cloud Editor

The steps here are the same as those of the first application case, so please refer to the first project to upload the program to Arduino Cloud Editor. The library and codes of this sample are as follows.

Library

blynk-library-master

Codes

#define BLYNK_TEMPLATE_ID           "TMPLxxxxxx"
#define BLYNK_DEVICE_NAME           "Device"
#define BLYNK_AUTH_TOKEN            "YourAuthToken"
#define BLYNK_PRINT Serial

#include <WiFi.h>
#include <WiFiClient.h>
#include <BlynkSimpleEsp32.h>

char auth[] = BLYNK_AUTH_TOKEN;
char ssid[] = "YourNetworkName";
char pass[] = "YourPassword";
BlynkTimer timer;
int inPin = D7;

void myTimerEvent() {
  if (digitalRead(inPin) == 0) {
    Blynk.virtualWrite(V3, "Intrusion alarm");
  }
}

void setup() {
  Serial.begin(115200);
  Blynk.begin(auth, ssid, pass);
  timer.setInterval(1000L, myTimerEvent);
  pinMode(inPin, INPUT);
}

void loop() {
  Blynk.run();
  timer.run();  
}
#define BLYNK_TEMPLATE_ID           "TMPLxxxxxx"
#define BLYNK_DEVICE_NAME           "Device"
#define BLYNK_AUTH_TOKEN            "YourAuthToken"
#define BLYNK_PRINT Serial

#include <WiFi.h>
#include <WiFiClient.h>
#include <BlynkSimpleEsp32.h>

char auth[] = BLYNK_AUTH_TOKEN;
char ssid[] = "YourNetworkName";
char pass[] = "YourPassword";
BlynkTimer timer;
int inPin = D7;

void myTimerEvent() {
  if (digitalRead(inPin) == 0) {
    Blynk.virtualWrite(V3, "Intrusion alarm");
  }
}

void setup() {
  Serial.begin(115200);
  Blynk.begin(auth, ssid, pass);
  timer.setInterval(1000L, myTimerEvent);
  pinMode(inPin, INPUT);
}

void loop() {
  Blynk.run();
  timer.run();  
}

Connect the device to Blynk

1. Sign up and log in to Blynk, then create a new template (select ESP32 as hardware and WiFi as the connection type).

2. Create a new device and choose "From template".

3. Select the template just created.

4. Enter the device to view its template ID, device name, and AuthToken.

5. Edit the dashboard to configure the gauge of the device.

6. Drag and drop Gauge to set up.

7. Set the Gauge TITLE & Datastream.

Result

When the PIR sensor has detected the presence of human beings, the message "intrusion alarm" will be reported to Blynk.

3. Environmental Data Monitoring

Description

• Connect to the WiFi "Beetle ESP32E", and the set password is 12345678
• Visit the website http://192.168.4.1/GET to get the environmental data information on the LAN
• Refresh the webpage to update the sensor data

Hardware List

1. FireBeetle 2 ESP32-E IoT Microcontroller ×1

2. Multifunctional Environmental Sensor ×1

Connection

Upload Codes to Arduino Cloud Editor

The steps here are the same as those of the first application case, so please refer to the first project to upload the program to Arduino Cloud Editor. The library and codes of this sample are as follows.

Library

DFRobot_EnvironmentalSensor

Codes

#include <WiFi.h>
#include <WiFiClient.h>
#include <WiFiAP.h>
#include "DFRobot_EnvironmentalSensor.h"
#if defined(ARDUINO_AVR_UNO)||defined(ESP8266)
#include <SoftwareSerial.h>
#endif
#define MODESWITCH        /*UART:*/0 /*I2C: 1*/
#if MODESWITCH
#if defined(ARDUINO_AVR_UNO)||defined(ESP8266)
  SoftwareSerial mySerial(/*rx =*/4, /*tx =*/5);
  DFRobot_EnvironmentalSensor environment(/*addr =*/SEN050X_DEFAULT_DEVICE_ADDRESS, /*s =*/&mySerial);//Create an object for broadcast address, which can configure all devices on the bus in batches
#else
  DFRobot_EnvironmentalSensor environment(/*addr =*/SEN050X_DEFAULT_DEVICE_ADDRESS, /*s =*/&Serial1); //Create an object for broadcast address, which can configure all devices on the bus in batches
#endif
#else
DFRobot_EnvironmentalSensor environment(/*addr = */SEN050X_DEFAULT_DEVICE_ADDRESS, /*pWire = */&Wire);
#endif

// Set the WIFI name and password
const char *ssid = "Beetle ESP32E";//WIFI name
const char *password = "12345678";//password

WiFiServer server(80);//The default web service port is 80


void setup() {
  //pinMode(myLED, OUTPUT);
  #if MODESWITCH
  //Initialize MCU communication serial port
#if defined(ARDUINO_AVR_UNO)||defined(ESP8266)
  mySerial.begin(9600);
#elif defined(ESP32)
  Serial1.begin(9600, SERIAL_8N1, /*rx =*/D3, /*tx =*/D2);
#else
  Serial1.begin(9600);
#endif
#endif
  Serial.begin(115200);
  Serial.println();
  Serial.println("Configuring access point...");

  //If you want to use the network without a password, delete it
  WiFi.softAP(ssid, password);
  IPAddress myIP = WiFi.softAPIP();
  Serial.print("AP IP address: ");
  Serial.println(myIP);
  server.begin();

  Serial.println("Server started");


    while(environment.begin() != 0){
    Serial.println(" Sensor initialize failed!!");
    delay(1000);
  }
  Serial.println(" Sensor  initialize success!!");

}

void loop() {

WiFiClient client = server.available();   // Check if server is available

  if (client) {                             // Check connectivity
    Serial.println("New Client."); 
    String currentLine = "";                // Create String variable to store data
    while (client.connected()) {            // Repeat when connected
      if (client.available()) {             // Check if there is data coming
        char c = client.read();             // Read the received data
        //Serial.write(c);                    // Print on serial monitor
        if (c == '\n') {                    // If a newline character is read

          //Clear the cached content
          if (currentLine.length() == 0) {
            client.print(" ");
            break;
          } else {    // Clear data stored by variable if there is a newline character
            currentLine = "";
          }
        } else if (c != '\r') {  // If a character except CR is obtained
          currentLine += c;      // Add the obtained character to the end of the variable
        }

        // Check if /GET is at the end
        if (currentLine.endsWith("/GET")) {
             //Read environmental data and print them on the web 
             client.print("Temp: "); client.print(environment.getTemperature(TEMP_C));client.println(" ℃");
             client.print("Humidity: "); client.print(environment.getHumidity());client.println(" %");
             client.print("Ultraviolet intensity: "); client.print(environment.getUltravioletIntensity());client.println(" mw/cm2");
             client.print("LuminousIntensity: "); client.print(environment.getLuminousIntensity());client.println(" lx");
             client.print("Atmospheric pressure: "); client.print(environment.getAtmospherePressure(HPA));client.println(" hpa");
             client.print("Elevation: "); client.print(environment.getElevation());client.println(" m");
        }
      }
    }
    // Disconnect
    client.stop();
    Serial.println("Client Disconnected.");
  }
  }
#include <WiFi.h>
#include <WiFiClient.h>
#include <WiFiAP.h>
#include "DFRobot_EnvironmentalSensor.h"
#if defined(ARDUINO_AVR_UNO)||defined(ESP8266)
#include <SoftwareSerial.h>
#endif
#define MODESWITCH        /*UART:*/0 /*I2C: 1*/
#if MODESWITCH
#if defined(ARDUINO_AVR_UNO)||defined(ESP8266)
  SoftwareSerial mySerial(/*rx =*/4, /*tx =*/5);
  DFRobot_EnvironmentalSensor environment(/*addr =*/SEN050X_DEFAULT_DEVICE_ADDRESS, /*s =*/&mySerial);//Create an object for broadcast address, which can configure all devices on the bus in batches
#else
  DFRobot_EnvironmentalSensor environment(/*addr =*/SEN050X_DEFAULT_DEVICE_ADDRESS, /*s =*/&Serial1); //Create an object for broadcast address, which can configure all devices on the bus in batches
#endif
#else
DFRobot_EnvironmentalSensor environment(/*addr = */SEN050X_DEFAULT_DEVICE_ADDRESS, /*pWire = */&Wire);
#endif

// Set the WIFI name and password
const char *ssid = "Beetle ESP32E";//WIFI name
const char *password = "12345678";//password

WiFiServer server(80);//The default web service port is 80


void setup() {
  //pinMode(myLED, OUTPUT);
  #if MODESWITCH
  //Initialize MCU communication serial port
#if defined(ARDUINO_AVR_UNO)||defined(ESP8266)
  mySerial.begin(9600);
#elif defined(ESP32)
  Serial1.begin(9600, SERIAL_8N1, /*rx =*/D3, /*tx =*/D2);
#else
  Serial1.begin(9600);
#endif
#endif
  Serial.begin(115200);
  Serial.println();
  Serial.println("Configuring access point...");

  //If you want to use the network without a password, delete it
  WiFi.softAP(ssid, password);
  IPAddress myIP = WiFi.softAPIP();
  Serial.print("AP IP address: ");
  Serial.println(myIP);
  server.begin();

  Serial.println("Server started");


    while(environment.begin() != 0){
    Serial.println(" Sensor initialize failed!!");
    delay(1000);
  }
  Serial.println(" Sensor  initialize success!!");

}

void loop() {

WiFiClient client = server.available();   // Check if server is available

  if (client) {                             // Check connectivity
    Serial.println("New Client."); 
    String currentLine = "";                // Create String variable to store data
    while (client.connected()) {            // Repeat when connected
      if (client.available()) {             // Check if there is data coming
        char c = client.read();             // Read the received data
        //Serial.write(c);                    // Print on serial monitor
        if (c == '\n') {                    // If a newline character is read

          //Clear the cached content
          if (currentLine.length() == 0) {
            client.print(" ");
            break;
          } else {    // Clear data stored by variable if there is a newline character
            currentLine = "";
          }
        } else if (c != '\r') {  // If a character except CR is obtained
          currentLine += c;      // Add the obtained character to the end of the variable
        }

        // Check if /GET is at the end
        if (currentLine.endsWith("/GET")) {
             //Read environmental data and print them on the web 
             client.print("Temp: "); client.print(environment.getTemperature(TEMP_C));client.println(" ℃");
             client.print("Humidity: "); client.print(environment.getHumidity());client.println(" %");
             client.print("Ultraviolet intensity: "); client.print(environment.getUltravioletIntensity());client.println(" mw/cm2");
             client.print("LuminousIntensity: "); client.print(environment.getLuminousIntensity());client.println(" lx");
             client.print("Atmospheric pressure: "); client.print(environment.getAtmospherePressure(HPA));client.println(" hpa");
             client.print("Elevation: "); client.print(environment.getElevation());client.println(" m");
        }
      }
    }
    // Disconnect
    client.stop();
    Serial.println("Client Disconnected.");
  }
  }

Result

Access the website from a cell phone, computer, etc. to get the results below (environmental data obtained from the multifunctional environmental sensor under LAN).

4. VOC Index Monitoring

Description

1. Display the VOC index on a screen in real-time

2. Prompt audios corresponding to the VOC index in different ranges

3. Monitor air quality change trends by collecting accurate VOC index data and then display data on Arduino IoT Cloud in a visual way that is easy to understand.

VOC Index           Air Quality             Suggested Action
0-100                Excellent           No ventilation needed
100-200               Good               No ventilation needed
200-300            Lightly Polluted      Ventilation suggested
300-400           Moderately Polluted    Increased ventilation suggested
400-500           Heavily Polluted       Strong ventilation suggested

Hardware List

1. FireBeetle 2 ESP32-E IoT Microcontroller ×1

2. SGP40 Air Quality Sensor ×1

3. DFPlayer Pro - A mini MP3 Player with On-board 128MB Storage ×1

4. I2C OLED-2864 Display ×1

Connection

Upload Codes to Arduino Cloud Editor

The steps here are the same as those of the first application case, so please refer to the first project to upload the program to Arduino Cloud Editor. The library and codes of this sample are as follows.

Library

• DFRobot_SGP40
• DFRobot_DF1201S

Codes

Arduino Editor

Transfer audio files into the MP3 Player module

Before use, connect the module to the computer using a USB cable and store the audio files in the MP3 player module.

Name the audio files as follows. Use the function 'DF1201S.playFileNum(/*File Number = */1);' to play the audio file with the specified number."

Connect the device to Arduino IoT Cloud

1. Open Arduino IoT Cloud, and click "ADD DEVICE".

2. Select "Set up a 3rd party device", and choose the device type as ESP32 and FireBeetle-ESP32.

3. You'll get the device ID and secret key, and you need to save them.

• 4. Create a thing and name it.

5. Create a variable VOC, and configure it as "int", "Read Only" and "On change"

6. Select the device to be associated with.

7. Then configure the network. Enter the WiFi name, password, and secret key saved in step 3.

8. Now the Things-related configuration is completed.

9. Click "Sketch" and "Open full editor" to write a program sketch.

10. Modify the routine and upload the final program.

11. Set up the dashboard

12. Set the linked variable, the minimum and maximum value in Widget Settings.

13. Set up the chart similarly.

Result

1. Display the VOC index on the OLED screen.

2. Play audio prompts corresponding to the VOC index in different ranges(Audios need to be put into the MP3 player in advance).

3. View the VOC index directly on the dashboard in real time.

Notice

Please note that the wiki resources for MP3 Player and ultrasonic ranging sensor in the kits are based on Arduino UNO, and you may need to make some changes in the codes to use them with ESP32.

MP3 Player (DFR0768)

Connection

Codes

When powered on, the module enters music mode and starts playing audio files, and the serial will print the current operation.

#include <DFRobot_DF1201S.h>

DFRobot_DF1201S DF1201S;
void setup(void){
  Serial.begin(115200);
  Serial2.begin(115200);
  while(!DF1201S.begin(Serial2)){
    Serial.println("Init failed, please check the wire connection!");
    delay(1000);
  }
  /*Set volume to 20*/
  DF1201S.setVol(/*VOL = */20);
  Serial.print("VOL:");
  /*Get volume*/
  Serial.println(DF1201S.getVol());
  /*Enter music mode*/
  DF1201S.switchFunction(DF1201S.MUSIC);
  /*Wait for the end of the prompt tone*/
  delay(2000);
  /*Set playback mode to "repeat all"*/
  DF1201S.setPlayMode(DF1201S.ALLCYCLE);
  Serial.print("PlayMode:");
  /*Get playback mode*/
  Serial.println(DF1201S.getPlayMode());
}

void loop(){
  Serial.println("Start playing");
  DF1201S.start();
  delay(3000);
  Serial.println("Pause");
  DF1201S.pause();
  delay(3000);
  Serial.println("Play the next song");
  DF1201S.next();
  delay(3000);
  Serial.println("Play the previous song");
  DF1201S.last();
  delay(3000);
  Serial.println("Start playing");
  DF1201S.fastForward(/*FF = */10);

  Serial.print("File number:");
  Serial.println(DF1201S.getCurFileNumber());
  Serial.print("The number of files available to play:");
  Serial.println(DF1201S.getTotalFile());
  Serial.print("The time length the current song has played:");
  Serial.println(DF1201S.getCurTime());
  Serial.print("The total length of the currently-playing song:");
  Serial.println(DF1201S.getTotalTime());
  Serial.print("The name of the currently-playing file:");
  Serial.println(DF1201S.getFileName());
  delay(3000);
  DF1201S.playFileNum(/*File Number = */1);
  while(1);
}
#include <DFRobot_DF1201S.h>

DFRobot_DF1201S DF1201S;
void setup(void){
  Serial.begin(115200);
  Serial2.begin(115200);
  while(!DF1201S.begin(Serial2)){
    Serial.println("Init failed, please check the wire connection!");
    delay(1000);
  }
  /*Set volume to 20*/
  DF1201S.setVol(/*VOL = */20);
  Serial.print("VOL:");
  /*Get volume*/
  Serial.println(DF1201S.getVol());
  /*Enter music mode*/
  DF1201S.switchFunction(DF1201S.MUSIC);
  /*Wait for the end of the prompt tone*/
  delay(2000);
  /*Set playback mode to "repeat all"*/
  DF1201S.setPlayMode(DF1201S.ALLCYCLE);
  Serial.print("PlayMode:");
  /*Get playback mode*/
  Serial.println(DF1201S.getPlayMode());
}

void loop(){
  Serial.println("Start playing");
  DF1201S.start();
  delay(3000);
  Serial.println("Pause");
  DF1201S.pause();
  delay(3000);
  Serial.println("Play the next song");
  DF1201S.next();
  delay(3000);
  Serial.println("Play the previous song");
  DF1201S.last();
  delay(3000);
  Serial.println("Start playing");
  DF1201S.fastForward(/*FF = */10);

  Serial.print("File number:");
  Serial.println(DF1201S.getCurFileNumber());
  Serial.print("The number of files available to play:");
  Serial.println(DF1201S.getTotalFile());
  Serial.print("The time length the current song has played:");
  Serial.println(DF1201S.getCurTime());
  Serial.print("The total length of the currently-playing song:");
  Serial.println(DF1201S.getTotalTime());
  Serial.print("The name of the currently-playing file:");
  Serial.println(DF1201S.getFileName());
  delay(3000);
  DF1201S.playFileNum(/*File Number = */1);
  while(1);
}

Ultrasonic Ranging Sensor（SEN0001）

Connection

Codes

Measure the distance between the sensor and the object in the detecting range.

int URECHO = D3; // PWM Output 0－50000US，Every 50US represent 1cm

unsigned int Distance = 0;
uint8_t AutomaticModelCmd[4] = {0x44, 0x02, 0xaa, 0xf0}; // distance measure command

void setup()
{
  Serial.begin(9600);           // Serial initialization
  delay(5000);                   // wait for sensor setup
  AutomaticModelSetup();        //Automatic measurement model set
}

void loop()
{
  AutomaticMeasurement();
  delay(100);
}


void AutomaticModelSetup(void)
{
  pinMode(URECHO, INPUT);
  for (int i = 0; i < 4; i++)
  {
    Serial.write(AutomaticModelCmd[i]);// Sending Automatic measurement model command
  }
}


void AutomaticMeasurement(void)
{
  unsigned long DistanceMeasured = pulseIn(URECHO, LOW);
  if (DistanceMeasured >= 50000) // the reading is invalid.
  {
    Serial.print("Invalid");
  }
  else
  {
    Distance = DistanceMeasured / 50;       // every 50us low level stands for 1cm
    Serial.print("Distance=");
    Serial.print(Distance);
    Serial.println("cm");
  }
}
int URECHO = D3; // PWM Output 0－50000US，Every 50US represent 1cm

unsigned int Distance = 0;
uint8_t AutomaticModelCmd[4] = {0x44, 0x02, 0xaa, 0xf0}; // distance measure command

void setup()
{
  Serial.begin(9600);           // Serial initialization
  delay(5000);                   // wait for sensor setup
  AutomaticModelSetup();        //Automatic measurement model set
}

void loop()
{
  AutomaticMeasurement();
  delay(100);
}


void AutomaticModelSetup(void)
{
  pinMode(URECHO, INPUT);
  for (int i = 0; i < 4; i++)
  {
    Serial.write(AutomaticModelCmd[i]);// Sending Automatic measurement model command
  }
}


void AutomaticMeasurement(void)
{
  unsigned long DistanceMeasured = pulseIn(URECHO, LOW);
  if (DistanceMeasured >= 50000) // the reading is invalid.
  {
    Serial.print("Invalid");
  }
  else
  {
    Distance = DistanceMeasured / 50;       // every 50us low level stands for 1cm
    Serial.print("Distance=");
    Serial.print(Distance);
    Serial.println("cm");
  }
}